The related applications relate to a power supply controller which can be used for controlling a plurality of isolating power supplies, such as switch mode power supplies or DC power converters, for providing controlled electrical power to loads. For example, the power supplies may provide different supply voltages to various electrical circuits on a circuit card on which the power supply controller is also provided.
In such a power supply controller, separate IC (integrated circuit) control units can be provided on the primary and secondary sides of a transformer that serves to maintain an electrical isolation barrier between input and output sides of the isolating power supplies. The transformer conveniently provides for signal coupling in both directions between the primary and secondary control units, and also for power transfer from its primary to its secondary side to supply operating power to the secondary control unit and any related circuits (for example, a non-volatile memory) of the power supply controller on the secondary side of the transformer.
As described in the related applications, the power supply controller and the signal coupling within it are arranged for controlling up to six power supplies. To this end, each of the primary and secondary control units has six converter state machines (CSMs), one for each of up to six controlled power supplies, as well as an input state machine (ISM) relating to an input or supply voltage.
A primary aspect of the control of the power supplies relates to their sequencing in accordance with conditions monitored by the power supply controller. Sequencing refers to an order in which, and parameters in dependence upon which, the power supplies are enabled in a power-up process, disabled or shut down in a normal power-down process, and/or disabled or shut-down in a fault situation. The monitored conditions include, for example, output voltages produced by the respective power supplies, and an input voltage of a power source which powers all of the power supplies and the power supply controller.
It is known to provide a power supply controller or sequencer which performs such functions for a plurality of power supplies. For example, one such power supply controller is known from “Modular Solid-State Power Sequencing”, Goodew et al., IBM Technical Disclosure Bulletin Vol. 15, No. 12, pages 3697-3699, May 1973. In that controller, modules each for control of a respective power supply are connected together in a fixed manner to power up the power supplies in sequence one after another, and to power them down normally in a reverse sequence. In the event of a fault, that controller powers down the power supplies in an order that depends on the module detecting the fault.
In different arrangements of power supplies it would be desirable to be able to provide relatively arbitrary sequence topologies for the respective power supplies, rather than only the fixed, linear sequence topology as disclosed by this prior art.
Accordingly, there is a need to provide an improved method of sequencing power supplies.